The present invention relates to a framing camera capable of producing a plurality of discrete framed patterns.
A framing camera is already known and an example is described by R. Kalibjian and S.W. Thomas in their article "Framing Camera Tube for Subnanosecond Imaging Applications", Rev. Sci. Instrum. 54 (12), December 1983, pp. 1626-1628.
FIG. 6 is a schematic representation of the constitution of the framing camera described in the above-cited reference. This framing camera consists essentially of a photocathode 51, a deflector 52 for scanning electron beams that have been emitted from the photocathode 51 in response to irradiation with a light beam carrying picture image information, an anode 54 having a plurality of slits 53-1 to 53-3, a deflector 55 for scanning electron beams that have passed through the slits 53-1 to 53-3 in the anode 54, and a phosphor screen 56 to be irradiated with the electron beams scanned with the deflector 55.
The operation of this framing camera proceeds as follows. Electron beams carrying information of a spatial picture image IM, that have been emitted from the photocathode 51, are scanned with the deflector 52 so as to sequentially pass through the slits 53-1 to 53-3 in the anode 54. By passing through the slits 53-1 to 53-3, electron beams having the picture image information as a temporal sequence are formed as shown by IM1 to IM3 and then directed toward the deflector 55. The deflector 55 performs another deflection of the electron beams to restore the picture image information of temporal sequence to the initial spatial picture image information before they irradiate the phosphor screen 56. As a result, a plurality of framed patterns (FM1 to FM3) whose number corresponds to that of the slits 53-1 to 53-3 (three in the case being described) are obtained on the phosphor screen 56.
The above-described prior art framing camera needs more than one slit to obtain a plurality of framed patterns. In addition, the number of framed patterns is uniquely determined by the number of slits and cannot be readily changed. As a further problem, the interval between individual framed patterns and the frame time are uniquely determined by the speed at which electron beams are swept by the deflectors 52 and 55 and this limits the flexibility in operation of the framing camera.